Home / 1,390.68-2,086.20-621

Finding the Fourth Proportional to 1,390.68, 2,086.20 and 621

Calculator

Solution

The fourth proportional to 1,390.68, 2,086.20 and 621 is: 931.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.68 : 2,086.20 = 621 : x
  2. Step 2: Convert to fraction form
    1,390.68/2,086.20 = 621/x
  3. Step 3: Cross multiply
    1,390.68x = 2,086.20 × 621
  4. Step 4: Simplify right side
    1,390.68x = 1,295,530.20
  5. Step 5: Solve for x
    x = 1,295,530.20/1,390.68
  6. Step 6: Final answer
    x = 931.58

Related Problems

Find fourth proportional to 695.34, 1,043.10 and 310.50
Half scale
Find fourth proportional to 2,781.36, 4,172.40 and 1,242
Double scale
Find fourth proportional to 1,391.68, 2,087.70 and 622
Similar ratio
Find fourth proportional to 2,086.02, 3,129.30 and 931.50
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.